The proposed studies will examine the effects of prenatal maternal "anxiety" in the rat on emotional reactivity and resistance to disease in adult offspring. Prenatal maternal "anxiety" will be induced by conditioning female rats before pregnancy to avoid electric shock stimulation on presentation of a light, and then preventing their ability to make the avoidance response during pregnancy. Offspring will be fostered at birth to control for postnatal maternal influences. As adults, the offspring will be administered tests of emotional reactivity, and tested for resistance to experimentally induced disease. In spite of the use of fostering procedures, it may be that characteristics of the young influenced by prenatal experiences may alter maternal responses to the young, thus potentiating the effects of the gestational environment. Some of these studies will therefore include observations of adult-pup relationships, including maternal responses to vocal emissions of pups whose biological mothers have been differentially manipulated during gestation. These observations of adult-pup interactions will be done in dual-chambered cages, which allow the mothers to leave the pups' cage at any time, and which permit 24 hour recording of mother-pup contact. Effects of prenatal experiences on suckling behavior of the pups will also be tested.